Should be fine - I'm sure many people use them that way - although I wouldn't transmit whilst another receiver or transceiver was switched on. There may be enough isolation between ports but personally I wouldn't risk it.

That may not be good advice you're getting. First of all, you absolutely DO want a switch that grounds the unused ports because it will offer higher isolation than a switch that does not. Secondly, if you are using high power, it doesn't make any difference whether the other rigs are turned on or not, they could still be subject to damage. At a TX power of a KW, each of the other rigs will see 1 mW of RF into their front ends. I wouldn't call that a high risk of damage, but it's a risk that I wouldn't take unless I knew exactly what devices were in the front end of each of the other rigs, what their damage thresholds are, and what front end protection exists (likely none). At 100W or less, you might be alright, but you'd better be careful,and be absolutely sue you know which rig is selected before you transmit with any of them (which holds true whether the unused ports are shorted or not).

I use two multipole antenna switches: the first at the input to my antenna tuner and the second between the tuner and multiple receivers and transceiver plus 400W linear. Between the second switch and each receiver I use a receiver front-end protection device (for example Array Solutions AS-RXFEP) to limit the rf voltage which can get to each receiver front end (the AS-RXFEP limits this to .3 mV).

Both antenna switches ground the unused ports, but I do not have confidence that this plus the other isolation characteristics of the switches is sufficient protection for my receivers' front ends.

I do not use the antenna switches built into my tuner for the same reason. The unused positions of the built-in switch are not grounded and the isolation between the positions is poorer than that of the antenna switches.

How do you make sense of conflicting recommendations? One way is to try to understand the situations that each respondent is envisioning andsee how well it matches what you are trying to do.

A good quality commercial switch may have 60dB of isolation, especiallyif it shorts the unused ports to ground. That means 1mW to the receiverwith 1kW from the transmitter, and virtually any receiver should toleratethat. (It may not matter whether the receiver is turned on or not.) Mostreceivers should handle 10mW, and many will take 100mW or more withoutdamage. (That's not to say they will work properly at those levels, but thatthe receiver won't be damaged.) So if you are running a 100W transceiverto a reasonably good switch on HF, you should be OK.

But not all switches are well built, especially those designed for CB orHF operation at a low price point (or home built.) A switch with 40dB ofisolation on 80m may drop to 30dB on 10m if the connecting wires insidethe box run parallel for some distance or common ground impedance amongthe ports.

The switches designed for VHF/UHF use, or those with the connectorsin a circle out the back or sides, tend to be better (in the latter case becausethey minimize the connecting lead length.) Those in a large rectangular boxthat require long connecting wires may be more problematic.

So at 100W on HF, you're probably OK in most situations. If you are runningmore power, or have a particularly sensitive receiver that needs protection, it would be worthwhile choosing a good quality switch.

I was recently confronted with the same question. My coaxial switch grounds unused ports. I rejected the plan because I was afraid that I might forget to switch in the correct radio and try to operate it into a dead short. Since my gear is old it doesn't have the "foldback" feature.

I was recently confronted with the same question. My coaxial switch grounds unused ports. I rejected the plan because I was afraid that I might forget to switch in the correct radio and try to operate it into a dead short. Since my gear is old it doesn't have the "foldback" feature.

The watchword here is 'listen'. If a grounding switch is used, even more so than a non-grounding one, if the transceiver is not switched to the antenna then you will likely hear NOTHING, no signals, no noise, nothing. Always listen prior to transmitting, no matter what your setup (mine is rig direct to antenna for one particular rig), not only is it polite as it prevents jumping on someones QSO, it can also prevent such damage. For the radios i have that are switched, I have a routing to exercise the switches prior to transmitting, listening on each setting of the switch. If im on the wrong port, it will become aparent when the correct one is selected and the noise/signals increase.

This is something that is drilled into me by my line of work - In what I do, if I select a transmitter to the wrong port i can cause massive damage and huge economic loss, not to mention lose my job. So everything is double checked before a control is sent.

Of course, if your selecting a transmitter only (seperate boat-anchors) then you cant listen! Excellent, high quality and accurate labelling, and a sensible check routine are all thats needed.

MRV: Of course your are absolutely correct in all respects! While I was working I had the same situation..... it was necessary to monitor closely every motion and adjustment I made on my panel boards.

However, with my radio setup and age, there is the excellent possibility of screwing the pooch. I maintain two separate diagrams under my desk glass showing what switches need to be in what position to operate. More importantly, since I have to swap cables on occasion I use these diagrams to keep track of what I'm doing.

Then there are times when I don't use the gear at all and have to refresh my failing memory before operating. At other times I use one particular setup and ignore the other and lose track of what is hooked to what.

To have an additional coaxial switch in line to deal with became too much. I'm now seriously considering a checklist like we used on our boilers.

If this sounds like a tottering old man with more than he can deal with, you're right!

If the answer is two (2), look at MFJ. They have a switch that connects radio A or B to antenna 1 or 2. you could use the antenna and a dummy load on the antenna side, and two radios on the radio side. Now if radio A is connected to antenna 1, radio B is connected to the antenna 2 (Dummy load).

Thanks guy's for the info, and it sounds like -all rigs off--ant switch to rig--turn rig on---turn rig off---ant switch to next rig--turn that rig on etc. RULE- All rigs off before switching ant switch !

I was recently confronted with the same question. My coaxial switch grounds unused ports. I rejected the plan because I was afraid that I might forget to switch in the correct radio and try to operate it into a dead short. Since my gear is old it doesn't have the "foldback" feature.

I'm not sure that a dead short is any different than a dead open in thisrespect. The actual impedance seen by the rig will depend on thelength of coax between the rig and the switch in any case. I haven'tused a ham rig yet that would fail due to a momentary test into a shortor open, long enough to see that the rig is properly connected. On voiceyou can just blow into the mic to get about 10% output power and seethat the power meter deflects. Similarly with a single dit on CW.

If you're worried about that, then you can get a switch with an extraset of contacts and wire them to light a lamp over the rig that is connected to the antenna, or get more fancy and wire PTT switchthrough them so you can't transmit on a radio that is not selected.

I asked the same question on this forum some time ago. I have been using a 3-way coax switch by Diamond for several years in this situation: one antenna feeding 2 transceivers and a receiver. It has worked fine with no problems. The Diamond switch is specified to 60dB isolation on each port. Just check and double-check that you have the right rig switched BEFORE you transmit!

I also have a 3-way Diamond switch that I use to feed the outputs from 3 radios through to a single amp/tuner/antenna. On 10m, if I transmit on one radio at 100W and tune one of the unused radios to the exact same frequency, I see an S meter reading of S9+60dB. That's a little more than 60dB isolation.

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